public class Demo1 {
    public static void main(String[] args) {
        Object locker1 = new Object();
        Object locker2 = new Object();
        Thread t1 = new Thread(() -> {
            synchronized (locker1){
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                synchronized (locker2){
                    System.out.println("hello t1");
                }
            }
        });
        Thread t2 = new Thread(() -> {
            synchronized (locker2){
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                synchronized (locker1){
                    System.out.println("hello t1");
                }
            }
        });
        t1.start();
        t2.start();
    }
}